Mapping of N-C Bond Formation from a Series of Crystalline Peri-Substituted Naphthalenes by Charge Density and Solid-State NMR Methodologies.

A combination of charge density studies and solid state nuclear magnetic resonance (NMR) 1 JNC coupling measurements supported by periodic density functional theory (DFT) calculations is used to characterise the transition from an n-π* interaction to bond formation between a nucleophilic nitrogen atom and an electrophilic sp2 carbon atom in a series of crystalline peri-substituted naphthalenes. As the N⋅⋅⋅C distance reduces there is a sharp decrease in the Laplacian derived from increasing charge density between the two groups at ca. N⋅⋅⋅C = 1.8 Å, with the periodic DFT calculations predicting, and heteronuclear spin-echo NMR measurements confirming, the 1 JNC couplings of ≈3-6 Hz for long C-N bonds (1.60-1.65 Å), and 1 JNC couplings of <1 Hz for N⋅⋅⋅C >2.1 Å.

Measuring multiple 17O-13C J-couplings in naphthalaldehydic acid: a combined solid state NMR and density functional theory approach.

A combined multinuclear solid state NMR and gauge included projected augmented wave, density functional theory (GIPAW DFT) computational approach is evaluated to determine the four heteronuclear 1J(13C,17O) couplings in solid 17O enriched naphthalaldehydic acid. Direct multi-field 17O magic angle spinning (MAS), triple quantum MAS (3QMAS) and double rotation (DOR) experiments are initially utilised to evaluate the accuracy of the DFT approximations used in the calculation of the isotropic chemical shifts (δiso), quadrupole coupling constants (CQ) and asymmetry (ηQ) parameters. These combined approaches give δiso values of 313, 200 and 66 ppm for the carbonyl (C[double bond, length as m-dash]O), ether (-O-) and hydroxyl (-OH) environments, respectively, with the corresponding measured quadrupole products (PQ) being 8.2, 9.0 and 10.6 MHz. The geometry optimised DFT structure derived using the CASTEP code gives firm agreement with the shifts observed for the ether (δiso = 223, PQ = 9.4 MHz) and hydroxyl (δiso = 62, PQ = 10.5 MHz) environments but the unoptimised experimental XRD structure has better agreement for the carbonyl group (δiso = 320, PQ = 8.3 MHz). The determined δiso and ηQ values are shown to be consistent with bond lengths closer to 1.222 Å (experimental length) rather than the geometry optimised length of 1.238 Å. The geometry optimised DFT 1J(13C,17O) coupling to the hydroxyl is calculated as 20 Hz and the couplings to the ether were calculated to be 37 (O-C[double bond, length as m-dash]O) and 32 (O-C-OH) Hz. The scalar coupling parameters for the unoptimised experimental carbonyl group predict a 1J(13C,17O) value of 28 Hz, whilst optimisation gives a value of 27 Hz. These calculated 1J(13C,17O) couplings, together with estimations of the probability of each O environment being isotopically labelled (determined by electrospray ionisation mass spectrometry) and the measured refocussable transverse dephasing (T2') behaviour, are combined to simulate the experimental decay behaviour. Good agreement between the measured and calculated decay behaviour is observed.

A Combined 25 Mg Solid-State NMR and Ab Initio DFT Approach to Probe the Local Structural Differences in Magnesium Acetate Phases Mg(CH3 COO)2 ⋠nH2 O (n=0, 1, 4).

Multinuclear (1 H, 13 C, 25 Mg) solid-state NMR data is reported for a series of magnesium acetate phases Mg(CH3 COO)2 ⋅ nH2 O (n=0 (two polymorphs), 1, 4). The central focus here is 25 Mg as this set of compounds provides an expanded range of local magnesium coordinations compared to what has previously been reported in the literature using NMR. These four compounds provide 10 distinct magnesium sites with varying NMR interaction parameters. One of the anhydrous crystal structures (α) has an MgO7 site which is reported, to the best of our knowledge, for the first time. For those phases with a single crystal structure, a combination of magic angle spinning (MAS) NMR at high magnetic field (20 T) and first principles density functional theory (DFT) calculations demonstrates the value of including 25 Mg in NMR crystallography approaches. For the second anhydrate phase (ß), where no single crystal structure exists, the multinuclear NMR data clearly show the multiplicity of sites for the different elements, with 25 Mg satellite transition (ST) MAS NMR revealing four inequivalent magnesium environments, which is new information constraining future refinement of the structure. This study highlights the sensitivity of 25 Mg NMR to the local environment, an observation important for several sub-disciplines of chemistry where the structural chemistry of magnesium is likely to be crucial.

Revisiting oversight and regulation of molecular-based laboratory-developed tests: a position statement of the Association for Molecular Pathology.

Since 2006, the US Food and Drug Administration, Congress, and other policymakers have explored the appropriate way to guarantee the clinical and analytical validity of laboratory-developed tests. In the past, the Association for Molecular Pathology has publicly urged the Food and Drug Administration to exercise caution in implementing regulatory changes that could potentially hinder innovation or interfere with the practice of medicine. In 2012, the Association for Molecular Pathology Professional Relations Committee chose to develop this paper with the goal of outlining the best methods for ensuring appropriate oversight and validation of molecular diagnostic procedures. At the conclusion of this process, the workgroup reaffirmed the Association's previous position that the Centers for Medicare and Medicaid Services Clinical Laboratory Improvement Amendments program can provide the appropriate level of oversight for the vast majority of diagnostic tests.

High-risk human papillomavirus detection in women with low-grade squamous intraepithelial lesions or higher-grade cytology using the Cervista HPV HR test.

OBJECTIVE: High-risk human papillomavirus (HR-HPV) persistence is thought to be necessary for the development of cervical cancer. Because not all cases of low-grade squamous intraepithelial lesion (LSIL) or higher-grade squamous intraepithelial lesion are associated with HR-HPV, detection of HR-HPV in women with these cervical abnormalities may be clinically useful for management. The aim of this study was to detect HR-HPV in women with LSIL or higher-grade cytology. MATERIALS AND METHODS: In a multicenter, prospective clinical study, residual liquid-based cytological specimens from 3,966 US women were analyzed. Women with LSIL or higher-grade cytology underwent colposcopy and cervical biopsy as clinically indicated. The test was used to detect HR-HPV in women with cytologically diagnosed LSIL or higher, with histological confirmation of cervical intraepithelial neoplasia 2 (CIN 2) or worse by a central review panel. RESULTS: Among subjects with LSIL or higher-grade cytology and complete data sets, 11.8% (41/347) were diagnosed with CIN 2 or worse; 82.1% (285/347) were HR-HPV positive. The prevalence of CIN 2 or worse and CIN 3 or worse was 14.4% (41/285) and 7.0% (20/285), respectively, among subjects who were HR-HPV positive. All subjects diagnosed with CIN 2 or worse (41/41) and CIN 3 or worse (20/20) tested positive for HR-HPV. Sensitivity and negative predictive value calculated for CIN 2 or worse were 100% (95% CI = 91.4%-100.0%) and 100% (95% CI = 94.2%-100.0%), respectively. Specificity and positive predictive value among these subjects were 20.3% (95% CI = 16.1%-25.1%) and 14.4% (95% CI = 10.8%-18.9%), respectively. CONCLUSIONS: Detection of HR-HPV in women with LSIL or higher-grade cytology using the HPV HR test may allow clinicians to further triage women for advanced clinical management.

Models for incomplete nucleophilic attack on a protonated carbonyl group and electron-deficient alkenes: salts and zwitterions from 1-dimethylamino-naphthalene-8-carbaldehyde.

The X-ray crystal structures of salts and zwitterionic Knoevenagel products from 1-dimethylamino-naphthalene-8-carbaldehyde show long N-C bonds between peri-groups which provide models for incomplete nucleophilic attack on a protonated carbonyl group and electron-deficient alkenes respectively. For the salts the N-C bonds lie in the range 1.625-1.638 Å with C-OH bonds intermediate in length between single and double bonds, while for the zwitterions the N-C bonds lie in the range 1.612-1.660 Å. The structural assignment of the former is supported by solid state (13)C and (15)N NMR studies on doubly isotopically-labelled material. Several zwitterions were converted to naphtha[1,8-bc]azepines by a mechanism involving the tertiary amino effect.

Age-stratified performance of the Cervista HPV 16/18 genotyping test in women with ASC-US cytology.

BACKGROUND: The objective of this study was to evaluate the clinical performance of the Cervista HPV 16/18 genotyping test for detection of human papilloma virus (HPV) 16 and 18 in cervical cytology specimens in women stratified by age. METHODS: In a multicenter, prospective clinical study, ThinPrep specimens were tested for the presence of HPV 16 and 18 using the HPV 16/18 genotyping test. Genotyping results from women with atypical squamous cells of undetermined significance or greater cytology were compared with local colposcopy and/or histology results. Sensitivity, specificity, and negative and positive predictive values (NPV and PPV) were determined. RESULTS: The prevalence of cervical intraepithelial neoplasia (CIN) 2(+) in subjects positive for HPV 16/18 was 6.6% and 4.1% for women <30 and ≥30 years of age, respectively. The sensitivity of the test was 70.0% (95% CI: 54.6-81.9) and 66.7% (95% CI: 46.7-82.0) in women <30 and ≥30 years, respectively. The NPV was 95.5% (95% CI: 93.4-97.6) in women <30 years and 96.6% (95% CI: 94.8-98.5) in women ≥30 years. Specificity was higher in women ≥30 years (79.9%; 95% CI: 74.9-84.2) than women <30 years (61.9%; 95% CI: 57.1-66.4). The PPV was 15.2% (95% CI: 12.7-19.1) in women <30 years and 21.9% (95% CI: 17.0-30.7) in women ≥30 years. CONCLUSIONS: The performance of the Cervista HPV 16/18 genotyping test for predicting ≥CIN 2 is what would be expected across the key ≥CIN 2 age strata. IMPACT: HPV 16/18 genotyping may help further stratify women with a greater potential to develop cervical cancer.

Development and regulatory strategies for drug and diagnostic co-development.

At the 5th FDA-Drug Industry Association (DIA) Workshop on 'Pharmacogenomics in Drug Development and Regulatory Decision Making', track four focused on the current thinking and issues in the co-development of therapeutic drugs or biologics, and their companion diagnostic products. Identification and validation of genomic and other biomarkers are becoming important components of drug-development strategies, and recent successes show the power of personalized approaches to change the benefit-risk paradigm for new drugs.

Clinical validation of the Cervista HPV HR and 16/18 genotyping tests for use in women with ASC-US cytology.

OBJECTIVE: High-risk (HR) human papillomavirus (HPV) testing is important in cervical cancer screening for triage to colposcopy. This study evaluated the clinical performance of the Cervista HPV HR and 16/18 genotyping tests for detection of HPV in cervical cytology specimens. METHODS: The tests were prospectively evaluated in a multicenter clinical study. DNA was extracted from approximately 4000 residual liquid-based cytology specimens collected during routine liquid-based Papanicolaou tests at standard of care visits and was assessed for the presence of HR HPV and/or HPV types 16 and 18. All women with cytology results of atypical squamous cells of undetermined significance (ASC-US) or greater underwent colposcopic examination and biopsies were collected. Test results were compared with local colposcopy and histology results from a central pathology review panel. RESULTS: There were 1347 subjects with complete data sets of cytology, HR HPV, colposcopy, and histology included in the analysis of the HPV HR test. Sensitivity of the HPV HR test for detection of cervical intraepithelial neoplasia (CIN) 2+ among women with ASC-US cytology was 92.8% (95% confidence interval [CI]: 84.1-96.9) and the negative predictive value (NPV) was 99.1% (95% CI: 98.1-99.6). Sensitivity for detection of > or =CIN 3 in women with ASC-US was 100% (95% CI: 85.1-100) and the NPV was 100% (95% CI: 99.4-100). The specificity of the test for detection of > or =CIN 2 and > or =CIN 3 was 44.2% (95% CI: 41.5-46.9) and 43% (95% CI: 40.3-45.7), respectively. The HPV 16/18 genotyping test also performed as expected in women with ASC-US cytology who were positive for HR HPV. CONCLUSION: The Cervista HPV HR test can be clinically used for detecting HR HPV types in conjunction with cervical cytology for use in triage of women with ASC-US cytology during routine cervical cancer screening.

Analytical performance of the Investigational Use Only Cervista HPV HR test as determined by a multi-center study.

BACKGROUND: Any HPV test designed to be utilized in cervical cancer screening programs should be highly validated both analytically and clinically. OBJECTIVES: The Investigational Use Only (IUO) Cervista HPV HR test is designed to detect 14 high-risk HPV types (16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66, and 68). The analytical performance of the Cervista HPV HR test was characterized in a multi-center study. RESULTS: Analytical sensitivity for the 14 high-risk HPV types that the test is designed to detect ranged from 1,250 copies to 7,500 copies per reaction depending on HPV type. Accuracy compared to PCR with bi-directional sequencing was 91.4% [95% CI: 86.5 95.0%]. The reproducibility, when tested at three different testing centers, resulted in an overall inter-run reproducibility (between day/within site) agreement of 98.8% [1-sided 95% Confidence Lower Limit = 96.9%] and an overall inter-site reproducibility (between site) agreement of 98.7% [1-sided 95% Confidence Lower Limit = 97.9%]. The Cervista HPV HR test showed no cross-reactivity with DNA from seven non-oncogenic HPV types or 17 different infectious agents at up to 10(7) copies per reaction. CONCLUSIONS: The analytical performance of the Cervista HPV HR test demonstrates sufficient analytical performance for use in cervical cancer screening. As with any clinical laboratory test, analytical characteristics must be evaluated in light of the clinical performance of this assay.

A comparative review of laboratory-developed tests utilizing Invader HPV analyte-specific reagents for the detection of high-risk human papillomavirus.

BACKGROUND: Testing for human papillomavirus (HPV) has emerged as an important component of cervical cancer screening and disease management. Analytic performance (sensitivity, specificity, positive predictive value, negative predictive value, accuracy) and clinical relevance are important criteria by which any new test must be reviewed. OBJECTIVE: This paper compares laboratory-developed tests, utilizing Invader analyte-specific reagents (ASRs) for the detection of oncogenic HPV DNA, to the Digene Hybrid Capture 2 test (HC2). In addition to accurately identifying the presence or absence of HPV, genotyping has emerged as an important consideration for risk stratification and patient management. This paper reviews all current relevant Invader HPV literature to explain how these results shape our current understanding of the topic.

Perioperative genomic profiles using structure-specific oligonucleotide probes.

OBJECTIVES: Many complications in the perioperative interval are associated with genetic susceptibilities that may be unknown in advance of surgery and anesthesia, including drug toxicity and inefficacy, thrombosis, prolonged neuromuscular blockade, organ failure and sepsis. The aims of this study were to design and validate the first genetic testing platform and panel designed for use in perioperative care, to establish allele frequencies in a target population, and to determine the number of mutant alleles per patient undergoing surgery. DESIGN/SETTING/PARTICIPANTS AND METHODS: One hundred fifty patients at Marshfield Clinic, Marshfield, Wisconsin, 100 patients at the Medical College of Wisconsin Zablocki Veteran's Administration Medical Center, Milwaukee, Wisconsin, and 200 patients at the University of Wisconsin Hospitals and Clinics, Madison, Wisconsin undergoing surgery and anesthesia were tested for 48 polymorphisms in 22 genes including ABC, BChE, ACE, CYP2C9, CYP2C19, CYP2D6, CYP3A4, CYP3A5, beta2AR, TPMT, F2, F5, F7, MTHFR, TNFalpha, TNFbeta, CCR5, ApoE, HBB, MYH7, ABO and Gender (PRKY, PFKFB1). Using structure-specific cleavage of oligonucleotide probes (Invader, Third Wave Technologies, Inc., Madison, WI), 96-well plates were configured so that each well contained reagents for detection of both the wild type and mutant alleles at each locus. RESULTS: There were 21,600 genotypes confirmed in duplicate. After withdrawal of polymorphisms in non-pathogenic genes (i.e., the ABO blood group and gender-specific alleles), 376 of 450 patients were found to be homozygous for mutant alleles at one or more loci. Modes of two mutant homozygous loci and 10 mutant alleles in aggregate (i.e., the sum of homozygous and heterozygous mutant polymorphisms) were observed per patient. CONCLUSIONS: Significant genetic heterogeneity that may not be accounted for by taking a family medical history, or by obtaining routine laboratory test results, is present in most patients presenting for surgery and may be detected using a newly developed genotyping platform.

Detection and differentiation of wild-type and vaccine mutant varicella-zoster viruses using an Invader Plus method.

We report the use of a prototype Invader Plus method (Third Wave Technologies, Inc., Madison, WI) for the qualitative detection of varicella-zoster virus (VZV) and differentiation of wild-type and Oka vaccine VZV. The analytical sensitivity of the VZV Invader Plus reagents is at 10 copies per reaction. A total of 174 skin and mucous swab specimens were used to validate the assay's performance. The sensitivity and specificity were 98.3% and 98.1%, respectively, in comparison to a PCR-EIA assay. A perfect 100% agreement was obtained when VZV wild-type and vaccine differentiation was performed on 54 VZV-positive swab specimens against an allele-specific FRET real-time assay. The Invader Plus method provides another reliable tool for qualitative detection of VZV and differentiation of wild-type and vaccine virus.

Phenotype-dependent and -independent actions of rosuvastatin on atherogenic lipoprotein subfractions in hyperlipidaemia.

This randomised, double-blind, placebo-controlled crossover study evaluated the effects of rosuvastatin (40 mg/day for 8 weeks) on atherogenic apolipoprotein B-containing lipoprotein subfractions. Subjects, recruited based on raised plasma triglyceride (TG) or low-density lipoprotein cholesterol (LDL-C), were divided into normotriglyceridaemic (NTG, n = 13; TG < 2.0 mmol/l) and hypertriglyceridaemic (HTG, n = 16; TG > or = 2.0 mmol/l) groups. Similar reductions on rosuvastatin were observed for both groups in LDL-C (NTG -60%; HTG -56%), apoB (both -49%), intermediate-density lipoprotein (NTG -57%; HTG -54%) and LDL circulating mass (NTG -52%, HTG -58%) (all P < 0.001 versus placebo), i.e., these changes were phenotype independent. Phenotype dependency in response was observed in HTG relative to NTG in concentration of small dense LDL (LDL-III) (NTG -44%, P = NS; HTG -69%, P < 0.001), very-low-density lipoprotein1 (NTG -18%, P = NS; HTG 46%, P < 0.01), and remnant-like particle cholesterol (NTG -31%, P = NS; HTG -48%, P < 0.05). Rosuvastatin reduced cholesteryl ester transfer protein (CETP) by 33% in NTG and 37% in HTG (both P < 0.001); a reduction in cholesteryl ester transfer activity (-59%, P < 0.001) was observed in HTG only. Rosuvastatin therefore, in addition to lowering LDL and apoB-concentrations, largely corrected the TG and LDL abnormalities in subjects who had the propensity to develop the atherogenic lipoprotein phenotype.

Remodeling of cerebrospinal fluid lipoprotein particles after human traumatic brain injury.

The association between possession of the APOE epsilon4 allele and unfavourable outcome after traumatic brain injury (TBI) suggests that the apolipoprotein E protein (apoE) plays a key role in the response of the human brain to injury. ApoE is known to regulate cholesterol metabolism in the periphery through its action as a ligand for receptor mediated uptake of lipoprotein particles (Lps). Greater understanding of cholesterol metabolism in the human central nervous system may identify novel treatment strategies applicable to acute brain injury. We report findings from the analysis of lipoproteins in the cerebrospinal fluid (CSF) of patients with TBI and non-injured controls, testing the hypothesis that remodeling of CSF lipoproteins reflects the response of the brain to TBI. CSF Lps were isolated from the CSF of controls and patients with severe TBI by size exclusion chromatography, and the lipoprotein fractions analysed for cholesterol, phospholipid, apoAI, and apoE. There was a marked decrease in apoE containing Lps in the TBI CSF compared to controls (p=0.002). After TBI there was no significant decrease in apoAI containing CSF Lps (CSF LpAI), but the apoAI resided on smaller sized particles than in control CSF. There was a population of very small sized Lps in TBI CSF, which were associated with the increased cholesterol (p=0.0001) and phospholipid (p=0.040) seen after TBI. The dramatic loss of apoE containing Lps from the CSF, and the substantial increase in CSF cholesterol, support the concept that apoE and cholesterol metabolism are intimately linked in the context of acute brain injury. Treatment strategies targeting CNS lipid transport, required for neuronal sprouting and synaptogenesis, may be applicable to traumatic brain injury.

Erythrocyte-containing versus crystalloid cardioplegia in the rat: effects on myocardial capillaries.

BACKGROUND: The purpose of this study was to investigate the effects of crystalloid and erythrocyte-containing cardioplegia on capillary morphology of the isolated erythrocyte-perfused rat heart. METHODS: Hearts from adult Sprague-Dawley rats were perfused throughout with resuspended sheep erythrocytes and subjected to the following protocols (n = 6, all groups): (1) 15 minutes nonworking and 30 minutes working heart mode (control; group 1); (2) as for group 1, with 30 minutes erythrocyte-containing (BL) or crystalloid (CR) cardioplegic arrest without reperfusion (groups 2BL and 2CR); (3) as for group 2, with 30 minutes nonworking reperfusion (groups 3BL and 3CR); and (4) as for group 3, with 30 minutes working heart mode (groups 4BL and 4CR). After each protocol troponin I from coronary effluent was measured. Corrosion casts were then made of the coronary microvasculature. Cast density was calculated as cast volume per left ventricular dry weight. Casts also underwent scanning electron microscopy. Analysis was by analysis of variance. Values are mean +/- standard deviation. RESULTS: Prearrest working heart coronary flow averaged 15.1 +/- 4.7 mL/min without any differences among groups. Coronary flow in group 4 working hearts was the same before and after either cardioplegia. Cardiac outputs were similarly consistent in all groups. Cast density in group 1 (control) was 9.60 +/- 1.17 x 10(-2) mm3/mg. It was unaltered by erythrocyte-containing cardioplegia, but after crystalloid cardioplegia (group 2CR), it was 6.52 +/- 0.93 x 10(-2) mm3/mg (p = 0.0001 versus group 1 and p = 0.0007 versus group 2BL). With 30 minutes of nonworking reperfusion (group 3CR, there was slight improvement in cast density at 7.60 +/- 0.90 x 10(-2) mm3/mg (p = 0.0072 versus group 1; p = 0.0242 versus group 3BL). No further improvement was seen in group 4CR. Electron micrographs showed circumferential angularities or narrowings in crystalloid-perfused, arrested hearts, consistent with ischemic damage. Troponin I rose significantly after reperfusion in all groups, but it was higher in crystalloid-perfused, arrested hearts: 0.054 +/- 0.013 microg/L versus 0.024 +/- 0.017 microg/L (p = 0.0273). CONCLUSIONS: Erythrocyte-containing cardioplegia maintained capillary density and morphology. Crystalloid cardioplegia produced capillary loss, visible abnormalities, and higher troponin I release. These hearts may be more vulnerable to myocardial damage during reperfusion than hearts perfused with erythrocyte-containing cardioplegic solution.

Lipolysis generates platelet dysfunction after in vivo heparin administration.

Heparin, when administered to patients undergoing operations using cardiopulmonary bypass, induces plasma changes that gradually impair platelet macroaggregation, but heparinization of whole blood in vitro does not have this effect. The plasma changes induced by heparin in vivo continue to progress in whole blood ex vivo. Heparin releases several endothelial proteins, including lipoprotein lipase, hepatic lipase, platelet factor-4 and superoxide dismutase. These enzymes, which remain active in plasma ex vivo, may impair platelet macroaggregation after in vivo heparinization and during cardiopulmonary bypass. In the present study, proteins were added in vitro to hirudin (200 units.ml(-1))-anticoagulated blood from healthy volunteers, and the platelet macroaggregatory responses to ex vivo stimulation with collagen (0.6 microg.ml(-1)) were assessed by whole-blood impedance aggregometry. Over a 4 h period, human lipoprotein lipase and human hepatic lipase reduced the platelet macroaggregatory response from 17.0+/-2.3 to 1.5+/-1.3 and 1.2+/-0.6 Omega respectively (means+/-S.D.) (both P <0.01; n =6). Other lipoprotein lipases also impaired platelet macroaggregation, but platelet factor-4 and superoxide dismutase did not. Platelet macroaggregation showed an inverse linear correlation with plasma concentrations of non-esterified fatty acids ( r (2)=0.69; two-sided P <0.0001; n =8), suggesting that heparin-induced lipolysis inhibits platelet macroaggregation. Lipoprotein degradation products may cause this inhibition by interfering with eicosanoids and other lipid mediators of metabolism.

Regulation of small dense LDL concentration in Korean and Scottish men and women.

Small dense LDL is now emerging as an important risk factor for coronary artery disease. The amount of the LDL III has been reported to differ between ethnic groups. To investigate differences in the distribution of LDL subfractions between Korean and Scottish populations, we measured the plasma concentration and percent distribution of three major LDL subfractions in age-and sex-matched, middle aged, healthy 124 Korean and Scottish subjects (32 Korean men vs. 32 Scottish men; 30 Korean women vs. 30 Scottish women). Body mass index and waist circumference did not differ between the two ethnic groups. Total cholesterol and LDL cholesterol concentrations were higher in Scottish men compared with Korean men (P<0.01), while plasma triglyceride concentration was higher in Korean men and women (P<0.01 in men, P<0.05 in women). HDL cholesterol concentrations in both Korean men and women were lower than that of their Scottish counterparts (P<0.05 in men; P<0.001 in women). Korean men had lower concentrations of total LDL (242+/-65 vs. 325+/-122 mg/dl, P<0.01), LDL I (24+/-18 vs. 60+/-36 mg/dl, P<0.001) and LDL II (110+/-56 vs. 196+/-78 mg/dl, P<0.001). In contrast, LDL III concentration was markedly higher in Korean men (108+/-75 vs. 70+/-65 mg/dl, P<0.05). Likewise, the percent of LDL I (10.0+/-7.3 vs. 19.1+/-10.1%, P<0.001) and LDL II (47.2+/-20.7 vs. 60.1+/-10.9%, P<0.01) were lower in Korean men, while that of LDL III was higher (42.8+/-24.9 vs. 20.8+/-15.0%, P<0.001). In the female population, there were no differences in total LDL and LDL I concentrations between Korean and Scottish. LDL II concentration was lower in Korean women (106+/-53 vs. 151+/-57 mg/dl, P<0.01). Korean women showed a higher percent of LDL III (24.8+/-24.7 vs. 14.2+/-5.9%, P<0.05) and a lower LDL II (47.8+/-19.1 vs. 61.0+/-10.0%, P<0.01). Multiple linear regression revealed that plasma triglyceride concentration was the most important determinant of the LDL III subfraction concentration in Korean men and women and in Scottish men. In Korean men, the LDL III concentration rose linearly through the whole range of plasma triglyceride concentration, whereas in Scottish men, there was a threshold at 108 mg/dl triglyceride above which there was a positive association. Korean women showed the same pattern as Scottish men. We suggest that LDL concentrations and LDL subfraction distributions are regulated differently in these two ethnic groups. The different relationships between triglyceride and LDL III subfraction in Koreans versus Scots suggest that other factors, such as hepatic lipase or cholesteryl ester transfer protein may additionally play a role determining the LDL subfraction profile.